The library[4] is written in C and provides functions which allow using regular expressions for searching over input text lines.

TRE uses extended regular expression syntax with the addition of "directions" for matching preceding fragment in approximate way.

This means that The library's author states[8] that time spent for matching grows linearly with increasing of input text length, while memory requirement is constant during matching and does not depend on the input, only on the pattern.

[9] It is the default regular expression engine in R.[10] However, if the project should be cross-platform, each target platform would need a separate interface.

Since other regular expression engines usually do not provide approximate matching ability, there is almost no concurrent implementation with which TRE could be compared.